The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

330 Later Production Steps
to the size of the tank. A typical 40-gallon (150 liter)
tank might have two or three baffles about three-fifths
the size of the interior section area.
Build the tank in two halves: the main box (with or
without baffles) and the top. To maximize space, you
Figure 26-23 A 40-gallon (150 liter) tank for Rogue Wave,
constructed using fillets and fiberglass tape on all inside
joints. <strong>The</strong> top of this tank forms a part of the cabin sole and
the tank is removable. Baffles are scalloped on the upper edge
so each compartment will vent. Notches at the bottom of the
scallops are for 3 ⁄8" (9mm) thick longitudinal plywood frames
to support the top.
Figure 26-24 A diesel fuel tank on Rogue Wave. <strong>The</strong> cockpit
sole forms the top.
can mold curved side panels that conform to the
contour of the hull out of sheets of plywood or veneer,
and then assemble them with standard sheet ply to
complete the tank. Depending on the size, shape, and
amount of support provided, 1 ⁄4" (6mm) plywood is
probably strong enough for most tanks up to 40
gallons. Thickness of plywood for tanks is mainly determined
by weight-per-square foot of unsupported area.
Supports for a 1 ⁄4" tank should be no more than 12"
(300mm) apart, assuming loading of 30 pounds per
square foot.
Holding tanks do need occasional cleaning, so we
always include a removable port in the middle to
provide access to all parts of the tank. Apply a layer of
6 oz (200g/m2 ) fiberglass cloth to the interior and apply
5 to 6 coats of epoxy to provide an excellent moisture
barrier. Try to make the interior surface as smooth as
possible to facilitate cleaning.
Windows and Ports
Windows provide light and, in many cases, much of
the ventilation needed in the interior. Ports or windows
which open yet can be made watertight are very difficult
to make yourself. <strong>The</strong> price of the manufactured
ones is reasonable, so it is best to purchase these items.
Traditionally, ports have been made of bronze or
aluminum, but in recent years a number of excellent
plastic windows have been introduced on the market.
Some of these plastic ports have unique design features,
and we have installed them on the most expensive boats.
You can easily manufacture and install at low cost nonopening
windows which only let in light. You can use
standard Plexiglas, but we highly recommend the use
of Lexan because it is harder, has better scratch
resistance, and is much stronger than Plexiglas. Choose
a type and thickness of window comparable in strength
to the cabin side or hull area that it is replacing.
To install windows as shown at the top of Figure 26-25,
drill and countersink holes and screw or bolt the Lexan
or Plexiglas to the cabin wall. You can install the
window on either the exterior or the interior surface.
We generally prefer the interior because the windows
look better, but interior installation is potentially
weaker and the cabin wall must be thick enough to